This leads to restricted root growth, reduction in transport of water and nutrients through the roots to the shoot, and eventually cell, root, and plant death.

Under anaerobic conditions, mitochondrial respiration and metabolism shifts to fermentation. This process produces a small amount of energy but also creates lactic acid, ethanol, and acetaldehyde, which are harmful to plants.

Factors That Influence Flooding Damage

Duration of Flooding

The longer the soil remains flooded or saturated, the greater the damage to the growing corn will be.

If flooding only persists for a few hours, effects on the plant can be reversed and long-term damage will likely be minimal.

The oxygen supply in flooded soil will be depleted within 24 to 48 hours.

Corn below the V6 growth stage can generally survive 1 to 4 days of flooding, depending on temperature.

Plants have a greater chance of survival if the growing point is not fully submerged or is submerged for less than 2 days.

Temperature

Warmer temperatures decrease the amount of time that corn can survive flooding.

Respiration is a temperature-dependent reaction. Warmer temperatures increase the rate of respiration, which accelerates the depletion of oxygen and buildup of harmful compounds.

Approx. duration of flooding corn can survive, by temperature:

Upper 70s or warmer = 1 day or less

Upper-60s to mid-70s = ~2 days

Mid-60 or cooler = ~4 days

Crop Growth Stage

Corn below the V6 growth stage is more susceptible to flooding than larger corn.

The corn plant's growing point is below ground until about V6

Younger plants and tissues have a higher rate of respiration due to the demands of rapidly dividing and enlarging cells.

Older plants have larger and deeper root systems that are more resilient against flooding damage.

Assessing Flooding Damage to Corn

After flooding subsides, evaluate plant survival by examining the growing point of plants:

Growing point tissue should be white to cream colored

Darkening and softening usually precedes plant death

Surviving plants should resume new leaf growth within 3 to 5 days after water drains from the field.

Even if plants survive, long-term growth and performance can be negatively affected.

Plants injured by flooding early in the season can be more susceptible to dry conditions later in the summer due to reduced root development.

Crazy Top in Corn

Plants that are flooded early in the season are susceptible to a disease known as crazy top.

Crazy top is caused by Sclerophthora macrospora, an oomycete pathogen that infects the growing point of submerged corn plants.

Nitrogen Loss From Flooding

Heavy rainfall and highly saturated soils early in the season can cause loss of fall- or spring-applied nitrogen from the soil.

Nitrogen loss potential is directly related to the amount of nitrogen in the nitrate form (Table 1). Nitrate (NO3-) is the form of nitrogen most readily taken up by the plant, but it is also the form with the greatest risk for loss.

Nitrogen in the ammonia (NH3) or ammonium (NH4+) form binds to negatively charged soil particles, protecting it from water-induced losses.

Ammonium is converted to nitrate in a bacteria-mediated transformation called nitrification.

The foregoing is provided for informational use only. Please contact your Pioneer sales professional for information and suggestions specific to your operation. Product performance is variable and depends on many factors such as moisture and heat stress, soil type, management practices and environmental stress as well as disease and pest pressures. Individual results may vary..